As is well known and understood, major damage during earthquake conditions result from a rupture of a gas or water main in a residential home. If the gas main, or pipe, cracks as a result of the tremor, the leaking gas could eventually be ignited by a pilot light at the hot water heater, furnace, or oven range, and an explosion results. If the crack or rupture is in the water main or pipe, flooding can ensue. Similar such problems will obviously be seen to be present in commercial and business establishments, as well, to magnify the potential problem and catastrophe. Clearly, a need for an automatically-operating shut-off valve of some type is needed to seal-off these mains or pipes once a seismic condition is detected. And, at the same time, it will be equally clear that a valve is required which can be easily re-set once the condition has cleared; and, further, to be of a type which operates independently of the existence of electricity, as electrical power may very well not be available where the earthquake would be such as to knock-down the electrical power system. At the same time, it would be additionally desirable to develop such a valve as would be operative to disable the electrical system at the home or commercial establishment even if it were continued to be supplied, as any electrical arcing produced as the system is damaged might, in and of itself, ignite any leaking gas that might be present.
Thus, it is an object of the invention to provide a shut-off valve for a gas or water main which automatically senses the existence of a tremor of a prescribed magnitude, and to operate, without any degree of electrical control, to automatically seal-off the gas or water main, yet be easily re-set once the tremors have terminated.